Telephone system.



PATENTED PEB. 14, 1905. D. W. CAMPBELL. ...K

TELEPHONE SYSTEM.

APPLIOATION FILED JUNE'ZI, 1904.

zy! fttorn ey .5.

No. 782,323. PATENTED PEB. 14, 1905.

D. W. CAMPBELL.

l TELEPHONE SYSTEM.

APPLIUATION FILED JUNE 21, 1904 2 SHEETS- SHEET a.

UNITED STATES Patented February 14, 1905.

PATENT OEEICE.

W. CAMPBELL, OF LA CROSSE, `VVISCON SIN, ASSIGNOR TO THE VOUGHT-BERGERCOMPANY, A CORPORATION OF WISCONSIN.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 782,323, dated February14, 1905.

i Application filed J une 21,A 1904. Serial No. 213,446.4

To all whom, t may concern:

4 that class commonly known as multiple central-energy telephoneapparatus.

One of the objects of this invention is to provide a telephone systemhaving., circuits which allow transmission of speech over solidconductors without the interference of relaywindings or relay-contacts.Another object is to provide a telephonecircuit When both stations areplugged up which permits the speech-waves to have a clear passage overboth connecting-plug cords without detrimental impedance or highresistance.

To these ends my invention consistsof'the features of construction andcombination of parts hereinafter described and claimed.

In the accompanying drawings, Figure l is a diagrammatic view of myimproved centralenergy telephone system, which illustrates a completecentral station and a pair of telephone instruments connectedtherewith,- the parts being shown in normal position-viz.,

the receiver at the subscribers station hung up and the plug at centralout of connection with the jack. Fig. 2 is a detail diagrammatic viewshowing the connection when the answering-plug is inserted in the jackat the central station and the receiver at the subscribers telephoneinstrument is down, and Fig. 3 is another detail diagrammatic viewshowing the connections when the receiver is hung up while the plugremains in said jack.

A and B represent two telephone instruments, C their respective lines, Dtheir switchboard-jacks and switchboard apparatus, and E the voperatorsconnecting-cord circuit for working the same.

The following description applies equally t0 both sides of the system,they being numbered in accordance with the specifications herein given.

The telephones A and B, of ordinary construction` have a switch-arm 3connected with the side 4 of the instrument line-circuit C and theprimary winding 14 of induction-coil I4a and condenser 3b connected withthe other side. The primary coil is also connected with the transmitter15, which in turn is connected with the upper contact-point 17ofvthe'switch. The lower contact-point 3c is connected with the callbell3, which in turn is connected with the condenser 3b. The receiver 2 isconnected with the secondary winding 3d of the induction-coil.

The central switchboard apparatus consists as follows: A battery F, thecurrent of which is fed to the apparatus at thelcentral exchange andtothe telephone instruments, has a pair of main feedwires 6 and 7'leading therefrom. The wire 4 of the instrument-circuit` is connectedwith the impedance-coil 5, which in turn is connected with the wire 6.The wire 4 is also connected with the spring side 35 of the jack D. Thewires 4 6, with their impedance-coil, constitute what I have chosen toterm the impedance-coil side .of the instrument and battery circuit. TheWire 12 of the instrument-circuit is connected with the relay 10, whichin turn is connected in series with the impedance-coil l8, leading fromthe wire 7 of the battery-circuit. The Wire 12 is also connected withthe spring 23 or sleeve' sideof the jack D. The thimbles 24, whichreceive the sleeve side of the operators plugs,

`is connected with the wire 9 between the jacklay 10 is energized byremoving the receiverl 2 from the switch-hook 3, the signal-lamp 20.

is illuminated.

The answering-plug G is of ordinaryconstruction and has its sleeve 27connected by the wire 26 Awith the relay 25, which in turn is connectedwith the main wire 7, leading from the battery, by means of the wires 25and 31. The tip 34 of the answering-plug G is connected, through, thewire 33, switch 42, contact-point 43, wire 32, relay 29, contactpoint30, armature 28, wires 44 and 31, with the wire 7 of the mainbattery-circuit. The armature 37 is permanently connected by the wire 31with the wire 7 of the battery-circuit and by the local circuit-wire 40,containing the lamp 39 and the contact-point 38, with the wire 6 of thebattery-circuit when the relay 2,9 is energized and the armature drawndown. The plug-circuits have connected therewith a local telephoneinstrument H and amagneto-generator I in the ordinary manner.

When a subscriber takes down a receiver 2 from the switch-hook 3, acircuit is established as follows: hook 3, (at telephone instrument A,)wire 4, impedance-coil 5, Wire 6, and positive battery, from negativebattery over wire 7, impedance-coil 8, wire 9, relaywinding 10, wires11, 12, 13, primary winding 14 of induction-coil, transmitter 15, wire16, contact-point 17, and back to hook 3. The establishment of thiscircuit energizes relay 10, causing it to pull up armature 18 andcornplete a circuit from battery through wire 7, armature 18, wire 19,lamp 20, and wire 6 back to positive battery. This gives the switchboardoperator the signal, whereupon the answering-plug G is inserted in jackD. This action short-circuits wire 22, relay 10, wire 11, jack-spring23, and jack-thimble 24. This denergizes relay 10, thereby releasingarmature 18 and cutting out lamp 20. At the same time a cleartalking-circuit is completed from negative battery, as shown in Fig. 2,through the relay 25, wire 26, plugsleeve 27, jack-sleeve spring 23,wires 12 and 13, induction-coil 14, transmitter 15, wire 16, hook-switchcontact 17, hook-switch 3, wire 4, impedance-coil 5, and wire 6 back topositive battery. The l energizing of relay 25 causes its armature 28 topull up, cutting out the relay 29. When the subscriberis throughtalking, he will then hang the receiver 2 on the hook 3, which opens theinstrument-circuit. This cuts the battery oif of the sleeve side of thejack and causes the relay 25 to release its armature 28. This armaturewill then resty against the relay-contact 30, and the current iows, asshown in Fig. 3, from negative battery through wire 31, armature 28,contact-point 30, relay-winding 29wire 32, wire 33 to thetip 34 of theplug Gr, jackspring 35, wire 36, impedance-coil 5, and Wire 6 topositive battery. This causes the armature 37 ofthe relay-winding29 toswing down and make contact with the contact-point 38.

A The current then iows from negative battery through wire 31, armature37, contact-point 38, disconnect-lamp 39, wires 40 and 6 to the positivebattery and notifies the operator that the instrument is not in use. Assoon as the plug G is pulled out of the jack all of the relay-armatu resfall into normal position and cut the lamp 39 out, as shown in Fig. 1.

Current is fed from the battery F to the telephone instrument whenconnected to the central apparatus through the impedance-coil 5 on oneside of the line. On the other side of the line the current is fedthrough the relay 10, impedance-'coil 8, and relay 25 in multiple. Therelay 10, impedance coil 8 in series, and relay 25 in multiple withthese two have a combined resistance equal to that of impedance-coil 5for the purpose of distrihuting the current equally without what iscommonly known as impedance effect or high resistance when thetalking-circuit is completed.

Having described my invention, what I claim as new, and desire toprotect by Letters Patent, is-

1. A telephone-line, a telephone-switch at the station thereoi` Jforchanging the circuit of the line in the use of the telephone, aspringjack for the line, a call-signal at the switchboard, a plug, aplug-circuit for making connection with said jack, a call-signal relayon the line-circuitat the switchboard, an impedance-coil in series withsaid relay, a disconnect-lamp circuit at the switchboard, a relay intheplug-circuit to open said disconnectlamp circuit when the telephoneis in use, and a main impedance-coil in theline-circuit equal inresistance tol that of the combined resistance of the call-signal relayand the call-signal impedance-coil in series and the disconi is madewith said jack and the telephoneout of use, and a main impedance-coil inthe'linecircuit equal in resistance to that of the combined resistanceof the call-signal relay and the call-signal impedance-coil in seriesand the disconnect-lamp relay in multiple with these two.

3. A telephone-line, a telephone-switch at the station thereof forchanging the circuit of the line in the use of the telephone, aspringjack for the line, a plug, a plug-circuit for IOO IIO

, the telephone, a jack for the line, a call-signal making connectionwith said jack, call and disconnect signaling means at the switchboard,a system of impedance and relay coils connected with said circuit forcontrolling the operation of said signaling means, and arnainimpedance-coil connected with said line and equal in resistance to thecombined resistance of said system oi' impedance and relay coils, forthe purposes specified.

4. In combination with a telephoneline, a telephone-switch at thestation thereof for changing the circuit of the line inthe use of at theswitchboard, a plug-circuit for making connection with said jack, acall-signal relay 10 at the switchboard, an impedance-coil 8in serieswith said relay, a relay 25 in said plugcircuit, an auxiliary relay 29also in said plugcircuit, a disconnect-lamp and circuit opened andclosed by said auxiliary relay, said relay 25 adapted to control theoperation of said auxiliary relay, and a main impedance-coil 5 in theline-circuit equal in resistance to the combined resistance of the relay25and the resistance of the relay l() and impedance-coil 8 in series.

5. A telephone-line` a telephone-switch at the station thereof forchanging the circuit of the line in the use of the telephone', a jackfor the line, a call-signal at the switchboard, a plug, a plug-circuitfor making connection with said jack, a disconnect-lamp, adisconnect-lamp circuit at the switchboard, a main impedance-coil in theline-circuit, and a system of relays and impedance-coils at theswitchboard `connecteol with said circuits having a combined resistanceequal to that of said main impedance-coil.

In testimony Whereofl have signed my name to this specification in thepresence of two subscribing Witnesses.

DANIEL W. CAMPBELL.

Witnesses: i

A. M. PRIDEAnx, MILLS TOURTELLOTTE.

